Fluid filter condition indicators



Aug. 6, 1968 N. o. ROSAEN 3,395,802

FLUID FILTER CONDITION INDICATORS Filed Dec. 16, 1966 4 Sheets-Sheet 1INVENTOR. NILS O. ROSAEN ATTORNEYS Aug. 6, 1968 N. o. ROSAEN FLUIDFILTER CONDITION INDICATORS 4 Sheets-Sheet 2 Filed Dec. 16, 1966 FIG. 2.

FIG. 4.

INVENTOR- NILS O. ROSAEN BY fi ATTORNEYS g- 6, 1968 N. o. ROSAEN3,395,802

FLUID FILTER CONDITION INDICATORS Filed Dec. 16, 1966 4 Sheets-Sheet 3INVENTOR NILS O. ROSAEN FIG- BY M,

ATTORNEYS United States Patent 3,395,802 FLUID FILTER CONDITIONINDICATORS Nils O. Rosaen, Bloomfield Hills, Mich., assignor to TheRosaen Filter Company, Hazel Park, Mich, a corporation of MichiganContinuation-impart of application Ser. No. 465,346,

June 21, 1965. This application Dec. 16, 1966, Ser.

16 Claims. (Cl. 210-90) ABSTRACT OF THE DISCLOSURE Indicators for theclogged condition of filter elements in fiuid filtering systems, eachcomprising an electrical circuit with the indicator in series with thefilter element. The resistance of the filter element varies accordinglyto its clogged condition and results in a signal displayed by theindicator.

Cross-reference to related application The present invention iscontinuation-in-part of application Ser. No. 465,346, filed June 21,1965, now abandoned.

Background of the invention The present invention relates to fluidfilter devices and more particularly to filter devices having novelmeans for sensing and indicating the clogged condition of the filterelements.

Filter elements for fluid filtering systems must be periodically cleanedor replaced. Heretofore many attempts have been made to provide filterdevices having easily cleanable filter elements in combination with areliable and accurate means of indicating the condition of the filterelements. The present invention provides such filter devices.

Summary of the invention According to the principles of the presentinvention, the clogged condition of the filter element is sensed andmeasured by placing the filter element in an electrical circuitincluding a visual indicator, or the like, of the electricalconductivity or resistivity of the element which is proportional to theextent of its clogged condition.

As will become more apparent as the description proceeds, one aspect ofthe present invention is to provide a filter device having a filterelement constructed of a plurality of individual beads. The beads arepreferably constructed of a material having a high electrical resistanceand are carried within a resilient and electrically insulated perforatedstructure intermediate the inlet and the outlet of the filter device.The filter element is connected in series with a source of electricityand an ammeter so that changes in electrical conductivity through thefilter element will be indicated on the ammeter. As the filter elementbecomes clogged, the resulting increase in pressure differential acrossthe filter element causes a compacting of the beads to thereby decreasethe electrical resistance across the filter element. This decrease issensed and indicated by the ammeter so that, by providing proper indiciaon the ammeter, the latter indicates the clogged condition of the filterelement.

Another aspect of the invention contemplates utilizing the decrease ofelectrical resistivity of an ordinary filter element becomingprogressively loaded superficially by dirt being less resistive, at theelectrical point of view, than the material forming the filter element.Such change in resistivity is detected by means of an electrical meter,such as an ammeter, placed in an electrical circuit including the filterelement.

It is therefore an object of the present invention to im- 3,395,8fi2Patented Aug. 6, 1968 ice prove fiuid filter devices by providing suchfilter devices with a filter element having means varying the electricalresistance across the element in response to changes in the cloggedcondition of the element and means indicating changes in the electricalresistance across the element to thereby indicate its clogged condition.

It is another object of the present invention to improve filter devicesby providing such devices with a readily cleanable filter elementcombined with a reliable and accurate means for indicating the cloggedcondition of the filter element.

It is yet another object of the present invention to improve thereliability of filter element condition indicating means by providing anew filter element constructed of a plurality of individual beads orballs of material having a high electrical resistance which are carriedWithin a resilient perforated container adapted to be disposedintermediate the inlet and outlet of a filter device so that increasesin the pressure differential across the element will more tightly packthe beads together to decrease the electrical resistance producedthereby by providing means associated therewith adapted for sensing andindicating the changes in the electrical resistance across the filteelement.

Yet a further object of the invention is to provide means electricallydetecting the clogged condition of a filter element when such conditionreaches a predetermined dangerous state.

Still further objects and advantages of the present invention willreadily occur to one skilled in the art upon reference to the followingdescription and the accompanying drawings in which like referencecharacters refer to like or equivalent parts throughout the severalviews, and wherein:

Brief description of the drawings FIG. 1 is a longitudinalcross-sectional view of an eX- arnple of an embodiment of the presentinvention;

FIG. 2 is a cross-sectional view taken substantially on line 2-2 of FIG.1;

FIG. 3 is an enlarged fragmentary view of a portion of the structureillustrated in FIG. 1;

FIG. 4 is an enlarged fragmentary view of a portion of the structureshown in FIG. 2;

FIG. 5 is a longitudinal cross-sectional view of another example ofembodiment of the present invention;

FIG. 6 is a plan view of the filter element in the embodiment of FIG. 5as seen substantially from line 6-6 of FIG. 5;

FIG. 7 is a longitudinal cross-sectional view of a further example ofembodiment of the present invention;

FIG. 8 is an enlarged fragmentary view of a portion of the structureshown in FIG. 7; and

FIG. 9 is a transverse cross-sectional view of the embodiment of FIGS. 7and 8 taken substantially along line 9-9 of FIG. 7.

Description of the preferred embodiments Now referring to the drawingsfor a more detailed description of the present invention, an example ofa first preferred filter device is therein illustrated in FIGS. 1-1 ascomprising a first housing member 10 and a second housing member 12preferably secured one to the other by a plurality of bolts 14 extendingthrough mating peripheral flanges 16 and 18 of the housing members 10and 12 respectively.

A filter chamber 20 is defined by the housing member 10 and 12 which maybe square, rectangular or circular in transverse section. An inlet port22 is provided in the housing member 10 and an oppositely positionedoutletport 24 is provided in the housing member 12 with the inlet port22 and the outlet port 24 open to the filter 3 chamber 20. The housingmember has a plurality of parallel posts 26 extending into the filterchamber from opposite sides of the inlet port 22. The posts 26 providethe means for carrying a bafile member 27 in a position spaced inwardlyof and extending across the inlet port 22. The housing member 12 hassimilar posts 28 extending into the filter chamber 20 from oppositesides of the outlet port 24 and having inner edges 29.

The inner peripheral edges of the housing member 10 and 12 are providedwith complementary recesses 30 which define the means for carrying aflat filter element 32 in the filter chamber 20 intermediate the inletport 22 and the outlet port 24. The filter element 32 preferablycomprises perforated support wall members 34 and 36 having inwardlyextending peripheral flanges 38 and 40 respectively. The flanges 38 and40 are secured one to the other along a pair of opposite edges, as canbest be seen in FIG. 2, and are of a reduced dimension along the otherpair of opposite edges as can best be seen in FIGS. 1 and 3, to permitdiametrically opposed plate contact members 42 to be securedintermediate the support Wall members 34 and 36, each plate contactmember 42 having a face portion 44 exposed intermediate the flanges 38and 40. A plurality of disconnected individual beads 46, as can best beseen in FIGS. 3 and 4, are carried within the Space defined by thesupport wall members 34 and 36 and flanges 38 and 40 and are in contactwith the inner surfaces of the plate contact members 42.

Insulator bushings 48 are mounted intermediate the housing members 10and 12 on opposite sides of the filter element 32 and provide the meansfor axially slidably carrying contact plungers 50, as can best be seenin FIG. 3, having inner discs 52 for engaging the plate contact members42. Springs 54, carried in recesses 56 provided in the bushings 48, urgethe discs 52 into engagement with the plate contact members 42. O-ringseals 58 and 60 carried by the bushings 48 prevent fluid leakage alongthe exterior surface of the bushings 48 and between the bushings 48 andthe shank of the contact plungers 50.

One of the contact plungers 50 is electrically grounded as indicateddiagrammatically at 62 in FIG. 1, and the other plunger 50 iselectrically connected through a conventional ammeter indicateddiagrammatically in FIG. 1 at 64 to a terminal of a source of electricalpower 66 having its other terminal grounded as shown at 68.

The support wall members 34 and 36 are preferably constructed of aresilient electrical insulating material so that the filter element 32is completely electrically insulated from the housing members 10 and 12.The contact plungers 50, the contact plate members 42 and the individualbeads 46 are preferably constructed of an electrically conductingmaterial, although the material of the beads has preferably a highresistivity such as beads of ceramics, glass, molded carbon resistormaterial, high resistivity stainless steel and the like, such that thepower source 66, the ammeter 64, the contact plungers 50, the platecontact member 42 and the beads 46 form a series electrical circuit.

The support wall members 34 and 36 being made of a resilient materialand posts 28 having their inner edges 29 closely adjacent the supportwall member 36, there results a compaction of the beads 46 within thesupport wall members 34 and 36 upon a pressure differential across thefilter element 32 that causes the support wall member 36 to engage theinner edges 29 of posts 28, the degree of compaction of the beadsdepending upon the degree of clogging of the filter element 32. As thefilter element 32 becomes clogged, the pressure differential across theelement increases. This increased pressure differential causes supportwall members 34 and 36 to flex toward the outlet port 24, and when thesupport wall member 36 engages the edges 29 of the posts 28 the areawithin the support wall members 34 and 36 decreases so that the beads 46are more tightly packed within this urea.

The beads 46 are preferably constructed of a material which, althoughcapable of conducting electricity has, as previously explained, a highresistance to electrical current, and as the beads become more tightlypacked, the current flowing through the filter element 32, and which isof the order of a few milliamperes, can be read on the ammeter 64. Sincethe decrease in resistance across the filter element 32 is proportionalto the degree of clogging thereof, by providing proper indicia ori'theammeter 64 the degree of clogging of the filter element 32can thus bevisually indicated exteriorly of the filter device.

Referring now to the example of embodiment of the present inventionillustrated in FIGS. 5-6, a filtering device is shown being in allrespects similar to the preceding embodiment, with .the exception thatthe filter element 32 is of a different construction and is shown ashaving a circular area such that the filter chamber 20 has acorrespondingly circular transverse section, and that posts 28 of thepreceding embodiment have been omitted. Surrounding the outlet port 24and extending into the filter chamber 20 are disposed a plurality ofposts 70 supporting an apertured plate member 72 adapted to support,preferably substantially at its center, a contact member 74 having athreaded portion 76 engaging a threaded bore 78 disposed in the platemember 74. The filter element 32 comprises an annular flange portion 80made of a material substantially having dielectric characteristics withrespect to electrical current conductance.

The annular flange member 80 is adapted to support a corrugatedfiltering wall member 82, made of, for example, woven plastic or glassfibers, cellulose, or the like, cemented, bonded or otherwise fastenedto the inner surface 84 of annular member 80. On two diametricallyopposed positions, annular member 80 is provided with recesses 86 inwhich are disposed small plate contact members 42 electricallyconnected, as shown at 88, to the filtering material 82. The filteringmaterial 82 is further provided with a metallic portion, substantiallyat its center, as shown at 90.

As in the precedently described embodiment, contact plungers 50 disposedin insulated bushings 48 are biased by springs 54 in such a manner thatdiscs or contacts 52 engage plate contact members 42. One of theplungers 50 is electrically connected to ground, as shown at 62, whilethe other is connected through ammeter 64 to a terminal of an electricalpower supply 66 having its other terminal grounded as shown at 68. Inaddition, the housing of the filter device is grounded by any convenientmeans such as shown at 92. During normal operation, the filteringmaterial 82 of filter element 32 is disposed in a series electricalcircuit which also includes the ammeter 64, and the electrical powersupply 66, the return being effected through ground. Ammeter 64 gives anindication which corresponds to the current flowing through thefiltering material 82. As the filter element 32 becomes graduallyclogged and coated on its inlet face with dirt which is better conductorof electricity than the filtering material 82 of filter element 32,ammeter 64 gives a deviation which corresponds to the current beingconducted in the series circuit, consequently, which corresponds to theamount of clogging of the filter element 32. As the filtering material82 becomes further and further clogged with dirt, the pressuredifferential across the filter element 32 increases and the elementtends to flex towards the outlet port 24 until metallic portion 90 ofthe filter element engages the face of electrical contact 74. Electricalcontact 74 being grounded, as being electrically connected to thehousing of the filter device, and this cuts the resistance of thefiltering material 82 approximately in half, with the result that theindicator means consisting of ammeter 64 suddenly jumps to apredetermined visual display giving an indication that the filterelement 32 is clogged to a point where it requires replacement.

It is evident that contact 74 may be adjusted to any appropriateposition, either towards or away from metallie portion 90 of the filterelement, such that the amount of permissible clogging of the filterelement may be predetermined.

It is also evident that the arrangement of FIGS. 5 and 6 may be modifiedto give, instead of a progressive indication of the amount of cloggingof the filter element 32, an all-or-nothing indication by omitting thecontact plunger 50 which is grounded at 62, and by making the filteringmaterial 82 of a material substantially conductive to electricity suchas a metallic fiber fabric or the like. In this manner, as long as thepressure differential across the filter element 32 is low enough contact74 is out of engagement with metallic portion 92, but as soon as thefilter element 32 is clogged to the point that it flexes filteringmaterial 82 towards the outlet port 24, contact 74 engages metallicportion 90 such that the series circuit including indicator 64 is closedand a visual display consisting of a light or an alarm may be sounded togive a warning of the excessive clogging of the filter element.

Referring now to FIGS. 7-9, which represent a further modification of afilter device according to the pres ent invention, a filter chamber isdefined by two half housings 10 and 12, substantially square orrectangular in transverse section, connected together at a junctionplane by means such as bolts 14. Half housing 10 is provided with theusual inlet port 22, a bafiie 28 supported by post members 26 beingdisposed within the filter chamber on its inlet side, so as to directthe flow of the fluid to be filtered substantially evenly over thesurface of the filter element 32. An apertured support plate 72 ismounted proximate the outlet port 24 by means of posts 70 and isarranged to be electrically insulated from halfhousing 12. This can bedone by making the posts 70, or support plate 72, or both, of adielectric material. Support plate 72 is provided with an electricalcontact 74 having a threaded body portion 76 engaging a threaded bore 78 substantially at the center of the support plate 72. A terminal 92 iselectrically connected, as shown by electric wire 94 passing throughinsulating bushing 96 pressed, threaded, or otherwise fastened in a wallportion of half housing 12, to a terminal of ammeter 64 having its otherterminal connected to a terminal of an electric power supply 66, theother terminal of which is connected to ground return.

The filter element 32 comprises two distinct portions which arerespectively mounting portion 98 and filtering portion 100, hingedrelatively to each other by any convenient means such as hinge 102 whichmay be, as shown, substantially like the well-known so-called pianohinges. Mounting portion 98 of the filter element 32 is made of amaterial being substantially a good conductor of electricity, and thehinged portion 100 of the filter element comprises a filtering materialportion 104 made of a material preferably having a high electricalresistance which is supported by a frame 106 made of a substantiallydielectric material except at its end, as shown at 108, which iscontiguous to and in electrical contact with the support portion 98through hinge 102. Filtering material 104 has an electrical contact 110disposed so as to correspond to electrical contact 74 when the filterelement is placed in normal position within the housing, as shown in thedrawings, by having its mounting portion 94 clamped between a ledge orflange 112 integral with halfhousing 12 on one side thereof and flangeportion 114 of half housing 12. As best seen in FIG. 8 the side offilter element 32 parallel to the hinged portion 102 is provided with acontact plate 42 electrically connected, as shown at 88, with filteringmaterial 104. The contact end 52 of a plunger 50 slid'ably disposed inan insulating bushing 48 pressed or threaded through the wall of halfhousing 12 is constantly urged by spring 54 into electrical contact withcontact plate 42. Plunger 50 is electrically connected to the sameterminal of indicator 64 as the terminal to which is connected contact74. A coil spring 114, best seen in FIG. 7, and disposed around pin 116dependent from or integral with half housing 12,is' arranged to normallybias the hinged portion of filter element 32 towards inlet port 22, theframe 106 of the filter element being thus in engagement with flange 114of half housing 110. Spring 114 is electrically insulated from thematerial 104 of the filter element 32 by means of dielectric washer 118.The housing of the filter device is normally grounded, as shown at 92,and a by-pass recess 120 is disposed in a wall of half housing 12, whereshown, for the purpose to be hereinafter explained. During normaloperation, filter element 32 occupies the position indicated in thedrawing in full line, and is electrically in a series circuit includingthe electrical power supply 66 and the indicator 64, which may be anammeter, in addition to the filtering material 104, the current returnbeing effected through the grounded connections. The resistance of thefiltering material 104 being substantially high, no or little deviationis shown on indicator 64.

As filter element 32 becomes further and further clogged with dirt whichhas a lesser electrical resistivity than the resistivity of thefiltering material 104, the current passing through the circuitincreases in proportion to the clogging of the filter element, and theclogged condition of the filter element 32 is visually displayed byindicator 64. When the clogged condition of the fiter element 32 reachesa predetermined value causing a pressure differential between inlet 22and outlet 24 of the device, such pressure differential becomes highenough to cause hinged portion 100 of filter element 32 to be displacedto the position shown in phantom lines in FIGS. 7 and 8, as soon as thatpressure differential is sufficient to overcome the force exerted byspring 114. Although in this position contact 52 no longer engagescontact plate 42, contact carried by filtering material 104 of thefilter element 32 engages contact 74, thus cutting the resistance placedin the series circuit to a much lower value which is indicated byindicator 64 which, as precedently mentioned, may also be arranged tooperate any appropriate alarm. In view of the presence of by-pass groove120, in spite of the clogged condition of the filtering element 104,fluid is still capable of flowing substantially freely across the filterdevice from inlet port 22 to outlet port 24 through the by-pass suchthat there is no danger resulting from a decrease in the How of fluid orinterruption thereof.

It is evident that in the embodiment of FIGS. 7-9 also, the contactplunger 50 and the associated contact plate 52 may be omitted, and thata substantially good current conducting material may be used asfiltering material 104, such that the device may be adapted to give anall or nothing indication of the clogged condition of the filterelement.

It will be evident to those skilled in the art that although theelectrical indicator providing an indication of the clogged condition ofthe filter element has been described as an ammeter connected in anelectrical series circuit so as to operate for all practical purposes asan ohmmeter adapted to give a visual display of the resistance of thefilter element, the electrical indicator may consist of a voltmeterconnected across the filter element so as to give a readingcorresponding to the voltage drop thereacross. Alternately, a bridgearrangement may be used, whereby the resistance of the filter element iscontinuously compared to a known resistance. In addition, the electricalvisual indicator may be supplemented, or replaced, by means giving analarm or shutting off the equipment incorporating the filter device as acomponent thereof.

It is apparent from the preceding description that new means have beendisclosed for sensing and indicating the clogged condition of filterelements for fluid systems. The particular means utilized have beenfound to be highly accurate and reliable and yet are much less expensiveto manufacture than many other heretofore known filter devices havingfilter element clogging indicating means.

It is also apparent that although there have been described but a fewembodiments of the invention, many 7. changes and modifications can bemade therein without departing from the spirit of the invention asexpressed in the appended claims. 1

I claim:

1.- A filter device for filtering a fluid comprising:

(a) means defining a filter chamber and an inlet and an outlet open tosaid filter chamber;

(b) a filter element in said filter chamber between said inlet andoutlet, said filter element being made of a filtering material having anelectrical resistance varying according to the clogged condition of saidfiltering material;

(c)-electric circuit means ment; and

(d) electrical indicator means included in said electric circuit forgiving an indication of the clogged conditionof said filter element inresponse to the change in resistance of said filtering material.

2. The device as defined in claim 1 wherein said filtering materialcomprises a plurality of individual beads of a relatively highelectrical resistance and means compacting said beads upon an increasein the pressure differential across said filter element for decreasingthe total resistance of said plurality of individual beads.

3. The device as defined in claim 2 and wherein said last mentionedmeans comprises a pair of resilient support wall members carrying saidbeads and means limiting deflection of one of said support members.

4. The device as defined in claim 1 further comprising means adapted tosuddenly vary the resistance of said filtering material for apredetermined clogged condition of said filter element.

5. The device as defined in claim 4 wherein said mentioned meanscomprises:

(a) a first stationary electrical contact;

(b) a second movable electrical contact on said filtering material;

() associated electrical connections between said contacts so as toelectrically substantially shorten the effective electrical length ofsaid filtering material when said contacts are engaged;

(d) said second contact being mounted on a portion of said filterelement adapted to move toward said first contact as a result of thefluid pressure differential across said fi-lter element so as to engagesaid first contact upon a predetermined pressure difierentialcorresponding to a predetermined state of clogging of said filterelement.

6. The device as defined in claim 5 wherein said filter element isflexibly movable toward said first contact.

7. The device as defined in claim 5 wherein said filter element ishingedly movable toward said first contact and is urged away from saidfirst contact by spring means.

8. The device as defined in claim 7 further comprising fluid by-passmeans for permitting fluid to by-pass said filter element when saidfilter element is hingedly moved to the position engaging said first andsecond contacts.

9. A filter device for filtering a fluid comprising:

(a) means defining a filter chamber and an inlet and an outlet open tosaid filter chamber;

(b) a filter element in said filter chamber between said inlet andoutlet, said filter element being made of a filtering material having anelectrical resistance varycomprising said filter eleing according to theclogged condition of said filtering material;

(c) an electrical circuit comprising in series said filtering material,a source of electrical power and an ammeter whereby the total resistanceof said filtering material in said filter element is continuouslymonitored; and

(d) said ammeter providing a visual display of the state of clogging ofsaid filter element as a function of a decrease in resistance of saidfiltering material resulting in an increase in electrical currentcirculating in said circuit.

10. The device as defined in claim 9 wherein said filtering materialcomprises a plurality of individual beads of a relatively highelectrical resistance and means compacting said beads upon an increasein the pressure diflerential across said filter element for decreasingthe total resistance of said plurality of individual beads.

11. The device as defined in claim 10 and wherein said last mentionedmeans comprises a pair of resilient support wall members carrying saidbeads and means limiting deflection of one of said support members.

12. The device as defined in claim 9 further comprising means adapted tosuddenly vary the resistance of said filtering material for apredetermined clogged condition of said filter element.

13. The device as defined in claim 9 wherein said mentioned meanscomprises:

(a) a first stationary electrical contact;

(b) a second movable electrical contact on said filtering material;

(c) associated electrical connections between said contacts so as toelectrically substantially shorten the effective electrical length ofsaid filtering material when said contacts are engaged; and

(d) said second contact being mounted on a portion of said filterelement adapted to move toward said first contact as a result of fluidpressure diflerential across said filter element so as to engage saidfirst contact upon a predetermined pressure differential correspondingto a predetermined state of clogging of said filter element.

14. The device as defined in claim 13 wherein said filter element isflexibly movable toward said first contact.

15. The device as defined in claim 13 wherein said filter element ishingedly movable toward said first contact and is urged away from saidfirst contact by spring means.

16. The device as defined in claim 15 further comprising fluid by-passmeans for permitting fluid to by-pass said filter element when saidfilter element is hingedly moved to the position engaging said first andsecond contacts.

References Cited UNITED STATES PATENTS 2,349,992 5/1944 Schrader 2l0-85X 2,727,634 12/1955 OMeara 2l0-445 2,732,948 1/1956 Koupal et al 210-356X 3,317,042 5/1967 Botsti'oer 55-274 X REUBEN FRIEDMAN, PrimaryExaminer.

F. SPEAR, Assistant Examiner.

